1. Technical Field
The present invention relates to a sliding element, in particular for an internal combustion engine, with a thermally sprayed coating, which comprises an exposed functional surface.
2. Related Art
In the area of the crank drive, great demands are nowadays made on the components thereof in terms of wear properties, thermal conductivity, strength and weight. For this reason, these components are increasingly produced from light metals. Mixed friction up to solid friction occurs at the contact surfaces, which can lead to high frictional losses as well as a high degree of wear (e.g. micro-welding by metal transfer from aluminium surfaces of the contact partners).
The composite structure has thus become the focus of development. To this end, thermal spraying offers excellent possibilities. By means of this process, it is possible to produce cost-effectively functional surfaces which meet these requirements and, moreover, improve the tribological properties of components in contact with one another.
Several thermally sprayed functional surfaces are currently known in technology, fully sprayed liners, thermally sprayed inner coatings and thermally sprayed annular groove reinforcements. So-called pseudo-alloys find application here. These are spray material structures, which comprise two or more different material phases in order to combine the advantages of the individual materials. A material phase usually comprises a light metal, such as for example an aluminium-based alloy, as well as at least one further, usually high-strength phase, such as for example silicon carbide.
It is known to obtain a communicating system, for example on cylinder running paths of internal combustion engines, by honing. Intersecting grooves thereby arise, which are connected to one another at the intersecting regions and thus constitute an open system overall. A drawback here is that an element sliding on the sliding surface, for example a piston ring of a piston of an internal combustion engine, pushes ahead of it the oil present in the grooves, instead of building up a hydrodynamic oil pressure. A mixed friction between the sliding partners involved thus arises at the groove edges.